Sockets for castors



iApri-1 14 1964 A. c. suma' man Vms'rcms INVENTOR ,4r/Qur Cea; 720771 l'BY n ATTORNEYS April 14, 1964 A. c. 'rooTH -3,128,495 socxET Fon cAs'roRs Filed June 26, 1961 2 Sheets-Shes?I 2 INVENToR ,4J/rar Cpe l Tw/L ATTORNEYS United States Patent Otlce 3,128,495 Patented Apr. 14, 1964 3,128,495 SOCKETS FOR CASTORS Arthur Cecil Tooth, Maidenhead, England, assigner to Flexello Castors & Wheels Limited, Slough, England Filed lune 26, 1961, Ser. No. 119,416 2 Claims. (Cl. 16-43) This invention relates to sockets intended to receive the upstanding stems of castors, such sockets as at present manufactured being composed of metal and in some cases being Idriven into the hole or recess provided or their reception in the article of furniture `or other structure with which the castor is to be associated.

The socket forming the subject of the present invention has been designed to fit into a cylindrical hole or recess off a certain nominal diameter in a variety of materials including solid-drawn and welded tubing, and hard and soft woods in both end and cross grain.

It has been found in practice that such holes or recess vary in diameter from the nominal up t'o nearly lg inch oversize and in some cases are oval instead of being circular. Furthermore such holes or recesses sometimes taper in their longitudinal direction.

The chief object of the invention is to evolve a oonstruction of sock-et which can be litted successfully, into such holes or recesses despite such variations in size or form and without pinching the castor stem which would naturally interfere with the free castoring movement of the wheeled castor.

A further object of the invention is to evolve a socket providing an adequate bearing surface for the stem and having self-lubricating properties.

A socket in accordance with the present invention is moulded from a suitable thermo-plastic material such as for example, nylon, the socket including nea-r its upper end a bearing surface for the upper end of the castor stem and having means for holding the stern 4in position within the socket once the stem has been pressed upwardly into the socket, but at the same time permitting of free rotational movement of the stem Within the socket, the socket being so shaped that it will be frictionally held in position within the hole or recess in which it is inserted `without yappreciable reduction in internal diameter of that part of the socket 'containing the stem.

Referring to the accompanying drawings:

FIGURE 1 is a side elevation of the socket;

FIGURES 2 and 3 are longitudinal sections of the socket in planes lying at right angles;

FIGURES 4, and 6 yare transverse sections on the lines A-A, B-B and C C respectively; and

FIGURE 7 is a plan view.

The socket illustrated is moulded from nylon or other suitable thermo-plastic material, the socket being generally indicated by reference numeral 1 and 'being 'of parallel cylindrical shape having a peripheral flange 2 at its lower end, the socket when `driven into a cylindrical hole in the yarticle ywith which the castor is to be associated, being adapted to receive the stem 3 'of the castor as shown in FIGURE 2.

The socket is formed with an internal diaphragm-like part 4 near its upr end having a domed under surface 5 which is intended to form a beaming surface against which the upper end of the castor stern 3 is adapted to abfut, the stem ybeing formed with the usual part spherical recess at its upper end. The part 4 is stiffened b-y an internally arranged web 6.

The socket is tapered at 7 at its upper end to facilitate its entry into the receiving hole or recess.

The stem 3 of the castor has only sufficient clearance in the socket to permit it to rotate freely therein and consequently it is very desirable that there shall ber no contraction of the walls of that part of the socket enclosing the stern when the socket is driven into position but that the socket shall be inmrlylheld in position within the hole or recess despite any variation in size or shape within reasonable limits.

4It is proposed therefore to provide the socket at its upper end with longitudinally arranged solid and virtually incompressible splines 8 of part circular cross-sectional shape, which as shown in FIGURE 4 project slightly from the periphery orf the cylindrical socket to ensure a very firm fricti'onal engagement with the walls of the boring. The socket at its lower end is provided with similar splines 9 but in this case as the splines surround the stem they `are recessed at the back as at 10 and as clearly shown in FlGURIES 2, 3 and 5 they are hollow so that they are resilient in nature. Consequently any small contraction in the splines will not produce a reduction in diameter of the boring in the socket with consequent binding of the socket walls on the stem of the castor.

To hold the stem in position within the socket, the walls of the socket 'at two diametrally opposite points are recessed as at 11 to form inwardly directed projections 12, the projections 112 due to the increased resiliency of the walls immediately surrounding the projections 12 overriding a shoulder formed by the upper end 13 of the stem when the stem is pushed upwardly into the socket, the projections interengaging a waist portion 1'4 of the stem to maintain the stem in position within the socket but at the same time permitting free rotation of the stem within the socket. The projections may be domed or otherwise shaped to form a lead to facilitate introduction of the stem. "To render the walls of the socket in the vicinity of the projections 12 more resilient the 'walls may be split at suitable points.

In use the castor socket is pressed lfirmly into the hole or recess, for example a recess in the leg of an article of furniture or into a tubular metal leg and is automatically maintained in position therein.

The stem of the castor is then 4inserted and pressed upwardly into position within the socket.

It will lbe appreciated that the only part of the socket whose internal diameter is likely to be reduced is the upper part into which the stem does not enter and consequently there will be no risk orf the socket pin-ching the stem and restricting its free rotational movement whilst lthe socket will at the same time easily accommodate itself to holes or recesses of varying diameter and form.

The socket being composed of nylon or other thermoplastic material having self-lubricating properties will not require lubrication during use and may be produced by an injection moulding process.

Although it 4is preferred to vuse a thermo-plastic mouldable material such .as for example nylon, it is thought possible to use one or other ci the thermo-setting materials such as for example polypropylene or a high impact polystyrene provided the material is sufliciently resilient to permit of outward displacement of the projections 12 and ensure their return movement to maintain lthe castor stem in position. As a further alternative it may be possible to construct the socket in metal and in the lform for example of a die casting.

I claim:

1. A socket for receiving la castor stem therein having a shoulder adjacent its upper end comprising a cylindrical elongated plastic resilient sleeve with an internal and external surface, said sleeve having an upper end and an open lower end for inserting a castor stem therein, said sleeve having solid axial splines circumrerentially dis- Iposed and projecting radially outwardly of said extern-al surface adjacent said upper end for frictionally gripping the Walls of a bore of an article in which said sleeve is disposed, a plurality of projections disposed on the i11- ternal surface of said sleeve and projecting radially inwardly, said projections being disposed axially in spaced relationship below said solid axial splines and adapted to be positioned below the shoulder of a castor stem inserted into the sleeve to detachably connect a castor'stem to the sleeve, hollowved out axial ribs circumerentially disposed arorund the lower end of said sleeve in spaced relationship below said projections, an outwardly extending peripheral flange disposed adjacent the lower edge of said open end of the sleeve for forming a bearing surface for a shoulder on a castor ldetaohably connected to said sleeve, and a disc shaped bearing member in said sleeve adjacent the 4lower end of said axial splines and spaced above said projections whereby a resilient socket member is provided for maintaining its bore diameter when compressed to allow a castor stern disposed therein to swivel freely.

2. The socket of claim l, ywherein sa and the ldisc shaped bearing member closes oli the upper end of said sleeve, fribs are joined to said disc bearing me- 5 termal surfacey of said sleeve.

References Cited in the le of this patent UNITED STATES PATENTS id sleeve is nylon, is horizontal and and reinforcement ber and the in- 

1. A SOCKET FOR RECEIVING A CASTOR STEM THEREIN HAVING A SHOULDER ADJACENT ITS UPPER END COMPRISING A CYLINDRICAL ELONGATED PLASTIC RESILIENT SLEEVE WITH AN INTERNAL AND EXTERNAL SURFACE, SAID SLEEVE HAVING AN UPPER END AND AN OPEN LOWER END FOR INSERTING A CASTOR STEM THEREIN, SAID SLEEVE HAVING SOLID AXIAL SPLINES CIRCUMFERENTIALLY DISPOSED AND PROJECTING RADIALLY OUTWARDLY OF SAID EXTERNAL SURFACE ADJACENT SAID UPPER END FOR FRICTIONALLY GRIPPING THE WALLS OF A BORE OF AN ARTICLE IN WHICH SAID SLEEVE IS DISPOSED, A PLURALITY OF PROJECTIONS DISPOSED ON THE INTERNAL SURFACE OF SAID SLEEVE AND PROJECTING RADIALLY INWARDLY, SAID PROJECTIONS BEING DISPOSED AXIALLY IN SPACED RELATIONSHIP BELOW SAID SOLID AXIAL SPLINES AND ADAPTED TO BE POSITIONED BELOW THE SHOULDER OF A CASTOR STEM INSERTED INTO THE SLEEVE TO DETACHABLY CONNECT A CASTOR STEM TO THE SLEEVE, HOLLOWED OUT AXIAL RIBS CIRCUMFERENTIALLY DISPOSED AROUND THE LOWER END OF SAID SLEEVE IN SPACED RELATIONSHIP BELOW SAID PROJECTIONS, AN OUTWARDLY EXTENDING PERIPHERAL FLANGE DISPOSED ADJACENT THE LOWER EDGE OF SAID OPEN END OF THE SLEEVE FOR FORMING A BEARING SURFACE FOR A SHOULDER ON A CASTOR DETACHABLY CONNECTED TO SAID SLEEVE, AND A DISC SHAPED BEARING MEMBER IN SAID SLEEVE ADJACENT THE LOWER END OF SAID AXIAL SPLINES AND SPACED ABOVE SAID PROJECTIONS WHEREBY A RESILIENT SOCKET MEMBER IS PROVIDED FOR MAINTAINING ITS BORE DIAMETER WHEN COMPRESSED TO ALLOW A CASTOR STEM DISPOSED THEREIN TO SWIVEL FREELY. 